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'Electronic’ DOped colloidal Nanocrystal Heterostructures with designed Interfacial composition: towards the development of new nano-device conceptS for lightning and energy Technologies

Final Report Summary - EDONHIST ('Electronic’ DOped colloidal Nanocrystal Heterostructures with designed Interfacial composition: towards the development of new nano-device conceptS for lightning and energy Technologies)

The EDONHIST project aimed at developing new generations of nanostructures with novel functionalities and their integration in advanced materials for real-world applications. To accomplish this goal the research activity was structured in three main tasks dealing with i) the design and synthesis of doped/undoped core-shell colloidal quantum dots (QDs) with highly controlled interfacial composition; ii) the photophysical investigation of the mechanisms responsible for light-emission and of their competing processes, and iii) the fabrication of working devices based on the optimized QDs. In all these fields the research carried out in the frame of the project produced cutting-edge results as proved by an impressive publishing tracking record. In particular, we published 22 works strictly related with the project activities on peer-reviewed journals and, even more importantly, this list includes paper published in Nature Photonics (2), Nature Nanotecnology, Science, Nano Letters (5), Advanced Functional Materials (2), and Nature Communications (2). Moreover, the obtained findings have been the subject of a large number of press releases (more than 300) on both national and international newspapers, magazines, websites and have been presented in several scientific and broad-audience TV-shows.

During the project new procedures for the synthesis of wavefunction engineered QDs have been developed which strongly reduces the growth time without detrimental effects on their optical properties. The photophysics of these novel materials has been deeply investigated demonstrating new antibunching mechanism and elucidating the influence of the surfaces/interfaces on their optical properties. As the last step of this research, many of these QDs have been exploited for practical applications which includes i) reversed oxygen sensors for highly emissive photoresponsive varnishes; ii) single particle ratiometric probes of pressure an of the intracellular pH; iii) light emitting diodes; iv) large-area colourless Luminescent Solar Concentrators (LSC) based both on heavy-metal-free colloidal QDs and on earth-abundant indirect-bandg silicon nanoparticles. These latter represent the main outcome of the full project. In particular, the last generations of fabricated LSCs, owing to the large effective spectral separation between the optical absorption and luminescence spectra of the QDs, are essentially unaffected by optical losses due to reabsorption of the guided luminescence. As a result, we obtained devices with record conversion efficiencies exceeding 3 %, despite their large area and high degree of transparency across the visible spectrum (70% transmittance), which renders them good candidates for the realization of building integrated photovoltaic (PV) elements such as PV windows. Monte Carlo ray-tracing simulations enabled us to model the optical performances of the LSCs for increasing lateral dimensions and slab thickness; these indicated that a peak optical power output as large as 70 W could be achieved using slabs with an area of one square meter embedded with optimized QDs with unitary photoluminescence quantum yield.

The obtained findings about LSCs give rise to three patent applications, and thanks to these achievements we founded the company Glass to Power (G2P), which is a spin-off of the University of Milano-Bicocca entirely supported by private investors (www.glasstopower.com). The aim of G2P is the industrialization and commercialization of photovoltaic windows based on the large-area LSC luminescent realized by using the QDs developed in the frame of the EDONHIST project.

At the moment of the project submission Dr Brovelli was employed as Assistant Professor with a three years contract. In 2014 Sergio Brovelli obtained a permanent faculty members position in the State University of Milano-Bicocca (confirmed Assistant Professor). Last year this position has been further upgraded to Associate Professor. Finally, Sergio Brovelli is not only one of the co-founder of G2P but he is actually also the chairman of scientific committee of the company.